Journal of Ultrasound in Medicine, Vol 8, Issue 8 417-420, Copyright © 1989 by American Institute of Ultrasound in Medicine

JOURNAL ARTICLE

Nonuniformity of fetal umbilical systolic/diastolic ratios as determined with duplex Doppler sonography

H. H. Kay, B. A. Carroll, J. D. Bowie, A. P. Killam and B. S. Hertzberg
Department of OB/GYN, Duke University Medical Center, Durham, NC 27710.

Fetal umbilical arterial systolic/diastolic (S/D) ratios are said to be uniform throughout the umbilical cord. We evaluated this phenomenon by performing duplex Dopper on 73 fetuses at three sites in the umbilical cord: near the placental origin, in the free-floating midcord, and near the fetal abdominal wall insertion. Twenty-one of 73 fetuses examined (29%) demonstrated pronounced nonuniformity of the S/D ratios with a discrepancy of 1 or greater between any two S/D measurements. Studies demonstrated the highest S/D ratios at the fetal abdominal wall and lowest S/D ratios at the placental origin. These findings suggest that umbilical arterial flow velocity waveforms (FVWs) and S/D ratios are not uniform throughout the cord in all patients. The significance of this finding is uncertain; however, this variability in umbilical cord flow velocity waveforms stresses the importance of identifying the portion of the umbilical cord from which S/D ratios are obtained.

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